The present invention relates to management of television broadcast resources, and more particularly to an automation protocol subscription service for assuring that an automation controller always has current status information about a master control switcher being controlled.
A television broadcast station combines video from one or more sources, such as tape recorders, character generators, other production switchers, digital video effects devices, ad inserters, etc., into a single video signal for transmission to television viewers. Such a station may have a plurality of such sources coupled to a master control switcher, such as the Grass Valley M2100 Master Control Switcher manufactured by Tektronix, Inc. of Wilsonville, Oreg. Where programming may be pre-planned in advance, various methods of automating the generation of the transmitted video signal have arisen.
An automation controller is coupled to control the master control switcher and has a xe2x80x9cplay listxe2x80x9d that outlines what sources need to be provided at the output of the master control switcher at what times and configurations to produce the transmitted video signal. The xe2x80x9cplay listxe2x80x9d is converted by an appropriate automation protocol into commands that are initiated by the automation controller to the master control switcher in order for the master control switcher to appropriately access the sources at its input to produce the desired transmitted video signal according to the play list. The automation controller generates the appropriate commands to the master control switcher based upon its knowledge of the current configuration/status of the master control switcher. Assuming a perfect environment and no manual intervention, theoretically once initialized the automation controller would always know the configuration/status of the master control switcher based upon the commands sent by the automation controller to the master control switcher.
However where there are errors in the execution of the commands by the master control switcher, or where manual intervention occurs, such as the insertion of news bulletins into scheduled programs, the configuration/status of the master control switcher changes and such changes are not known to the automation controller. The result may be catastrophic. As one example of a catastrophic effect, an operator may manually take a new source on-air. Since the automation controller does not know of this change in the master control switcher configuration/status, it issues a command to do the same, but instead results in taking the new source off-air. Since commercials are the most frequently transitioned sources on a master control switcher, this results in lost air-time for one or more commercials and lost revenue for the customer.
Therefore before the commands for each event on the play list are sent by the automation controller to the master control switcher, a status check command is sent to the master control switcher to determine what the configuration/status is first so that the automation controller may update its knowledge of the master control switcher configuration/status and generate the appropriate commands for the next event in the play list. Even in this situation, since the status query is usually generated several seconds prior to the actual event commands, there is the possibility that the configuration/status of the master control switcher may change in the short time interval between the status query and the event commands.
What is desired is a method of maintaining knowledge of a master control switcher at an automation controller up to actual execution of event commands from the automation controller to the master control switcher.
Accordingly the present invention provides an automation protocol subscription service that allows the master control switcher to notify the automation controller of any configuration/status changes that occur between commanded events to that the automation controller""s knowledge of the master control switcher configuration/status is always current. A new automation protocol subcommand is used to set up a subscription service with the master control switcher, and a new subscription command class is used to provide a response to the automation controller when a change in one of the subscribed services occurs at the master control switcher. In this way the [knowledge of the] automation controller""s knowledge of the master control switcher configuration/status is always current so that proper. commands are sent to execute events from a play list at the master control switcher.
The objects, advantages and other novel features of the present invention are apparent from the following detailed description when read in conjunction with the appended claims and attached drawing.